---
title: AudioNode.connect(AudioParam)
slug: orphaned/Web/API/AudioNode/connect(AudioParam)
translation_of: Web/API/AudioNode/connect(AudioParam)
original_slug: Web/API/AudioNode/connect(AudioParam)
---
<p>{{ APIRef("Web Audio API") }}</p>

<div>
<p>允许我们将当前节点的一个输出连接到音频参数的一个输入，并允许通过音频信号控制参数。<br>
 使AudioNode输出连接到多个AudioParam，并将多个AudioNode输出连接到单个 AudioParam，同时多次调用connect()。因此支持Fan-in and fan-out。<br>
  AudioParam可以从连接到它的任何AudioNode输出获取渲染的音频数据，并通过下混合将其转换为单声道（如果本身不是单声道的话）。然后，它将其他这样的输出和固定参数混合（ AudioParam的值通常没有任何连接），包括为参数调度的任何时间的变化。<br>
 因此，可以通过将AudioParam的值设置为中心频率来选择AudioParam将要更改的范围，并使用音频源和AudioParam之间的GainNode来调整AudioParam更改的范围。</p>
</div>

<h2 id="Syntax">Syntax</h2>

<pre class="brush: js;highlight[11]">var lfo = audioCtx.createOscillator();
lfo.frequency.value = 2.0; // Hz, two times per second

var lfoGain = audioCtx.createGain();
lfoGain.gain.value = 0.5;

// this is the parameter that is going to be modulated
var gain = audioCtx.createGain();
gain.gain.value = 0.5;

// Oscillators go from -1 to 1
// Make it go from -0.5 to +0.5 by connecting it to a GainNode with a gain value of 0.5
lfo.connect(lfoGain);

// because the value of the gain.gain AudioParam is originaly 0.5, the value is added, and it will go from 0.0 to 1.0
lfoGain.connect(gain.gain);

lfo.connect(gain.gain);</pre>

<div class="note">
<p><strong>Note</strong>: There can only be one connection between an output from one specific <code>AudioNode</code> and an {{ domxref("AudioParam") }}. Multiple connections to the same termini are equivalent to a single such connection (the duplicates are ignored).</p>
</div>

<h3 id="Description" name="Description">Returns</h3>

<p>Void.</p>

<h2 id="Examples" name="Examples">Example</h2>

<p>In this example, we will be altering the gain value of a {{domxref("GainNode")}} using an {{domxref("OscillatorNode")}} with a slow frequency value. This technique is know as an <em>LFO</em>-controlled parameter.</p>

<pre class="brush: js;highlight[8,9]">var AudioContext = window.AudioContext || window.webkitAudioContext;

var audioCtx = new AudioContext();

// create an normal oscillator to make sound
var oscillator = audioCtx.createOscillator();

// create a second oscillator that will be used as an LFO (Low-frequency
// oscillator), and will control a parameter
var lfo = audioCtx.createOscillator();

// set the frequency of the second oscillator to a low number
lfo.frequency.value = 2.0; // 2Hz: two oscillations par second

// create a gain whose gain AudioParam will be controlled by the LFO
var gain = audioCtx.createGain();

// connect the LFO to the gain AudioParam. This means the value of the LFO
// will not produce any audio, but will change the value of the gain instead
lfo.connect(gain.gain);

// connect the oscillator that will produce audio to the gain
oscillator.connect(gain);

// connect the gain to the destination so we hear sound
gain.connect(audioCtx.destination);

// start the oscillator that will produce audio
oscillator.start();

// start the oscillator that will modify the gain value
lfo.start();</pre>

<h2 id="Parameters" name="Parameters">Parameters</h2>

<dl>
 <dt>Destination</dt>
 <dd>The {{ domxref("AudioParam") }} you are connecting to.</dd>
 <dt>Output (optional)</dt>
 <dd>An index describing which output of the current <code>AudioNode</code> you want to connect to the {{ domxref("AudioParam") }}. The index numbers are defined according to the number of output channels (see <a href="/en-US/docs/Web/API/Web_Audio_API/Basic_concepts_behind_Web_Audio_API#Audio_channels">Audio channels</a>.)  If this parameter is out-of-bound, an <code>INDEX_SIZE_ERR</code> exception is thrown.</dd>
</dl>

<h2 id="Specifications">Specifications</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName('Web Audio API', '#widl-AudioNode-connect-void-AudioParam-destination-unsigned-long-output', 'connect(AudioParam)')}}</td>
   <td>{{Spec2('Web Audio API')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>

<div>{{CompatibilityTable}}</div>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari (WebKit)</th>
  </tr>
  <tr>
   <td><code>connect</code><code>(AudioParam)</code></td>
   <td>{{CompatVersionUnknown}} {{property_prefix("webkit")}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Firefox OS (Gecko)</th>
   <th>IE Phone</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td><code>connect</code><code>(AudioParam)</code></td>
   <td>{{CompatNo}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="See_also">See also</h2>

<ul>
 <li><a href="/en-US/docs/Web/API/Web_Audio_API/Using_Web_Audio_API">Using the Web Audio API</a></li>
</ul>